On a 2006 Ford Taurus 3.0 L engine, the 'Check Charging System' Light came on on the dashboard. At the time it was at night so the headlights were on as well as the A/C, radio, etc.

I tested the voltage on the battery with the vehicle off and got 12.79 volts, then I started it up and got 12.5 volts. With the headlights on the reading was around 12.45 volts. At no time during the testing did the dashboard light come on, it only comes on occasionally while driving and stays on for around 15-20 seconds or so. It seems as if the light is more likely to come on with the A/C running that without it.

The battery was replaced probably around 8 months ago, and the wire running off the alternator looks in tact completely and is tightened down all the way. There's also another wiring harness going to the alternator which i think controls the voltage regulator and it's also on all the way. I was thinking it could be a bad alternator, what do you guys think?

Also how difficult is it to replace on this vehicle, it looks pretty straightforward but looks can be decieving sometimes!

I figured the problem was the alternator, but the first time the dashboard light came on, my dad had Sears test the system and they came back and told him that everything's fine and that Ford's Alternators rarely go bad. They went on to say that the light probably came on because it was a hot day.

I didn't buy any of that and thats why i tested it myself after he got home, i figured it should be putting out at least 13 volts at idle.

Is this job as straightforward as it looks? remove the wires, remove the belt, remove the mounting bolts, etc. It didn't look like there would be anything in the way but i just wanted to get an expert's opinon.

Do the following tests and post back the results. Know that amperage test is almost always overlooked when test an alternator. Even if voltage is within threshold what good is voltage with the (PUSH) from amperage? Alternator voltage test

Make sure all your accessories and lights are turned off. Have an helper rev the engine up 2500 rpm. With a multimeter set on the DC scale measure the voltage across the battery terminals. Make sure the red lead of the multimeter is on the positive battery terminal and the black lead is on the negative battery terminal. With the engine at 2500 rpm’s the voltage reading on the meter should read from 13.5 volts to 14.4 volts. It’s necessary for an alternator to generate a larger voltage than the battery's rated voltage to overcome the internal resistance of the battery. If the voltage reading on the voltmeter is 12 volts or less you could have a failed alternator.

Alternator amperage test Connect the positive lead of the multimeter to the positive output on the rear of the alternator. Now connect the negative lead of the multimeter to the negative output of the alternator. With the engine running turn on all your electric accessories and lights and raise the idle to 1200 rpm. Read the meter. The alternators amperage output must never reach its maximum available output. (Example a 90 amp alternator should run no higher than 88 amps.) If an alternator is producing it's maximum capacity amperage, it will overheat and fail. Do the following tests and post back the results. Know that amperage testing is almost always overlooked when testing an alternator. Even if voltage is within threshold what good is voltage without the (PUSH) from amperage? Alternator voltage test

Make sure all your accessories and lights are turned off. Have an helper rev the engine up 2500 rpm. With a multimeter set on the DC scale measure the voltage across the battery terminals. Make sure the red lead of the multimeter is on the positive battery terminal and the black lead is on the negative battery terminal. With the engine at 2500 rpm’s the voltage reading on the meter should read from 13.5 volts to 14.4 volts. It’s necessary for an alternator to generate a larger voltage than the battery's rated voltage to overcome the internal resistance of the battery. If the voltage reading on the voltmeter is 12 volts or less you could have a failed alternator.

Alternator amperage test Connect the positive lead of the multimeter to the positive output on the rear of the alternator. Now connect the negative lead of the multimeter to the negative output of the alternator. With the engine running turn on all your electric accessories and lights and raise the idle to 1200 rpm. Read the meter. The alternators amperage output must never reach its maximum available output. (Example a 90 amp alternator should run no higher than 88 amps.) If an alternator is producing it's maximum capacity amperage, it will overheat and fail.

Do the following tests and post back the results. Know that amperage test is almost always overlooked when test an alternator. Even if voltage is within threshold what good is voltage with the (PUSH) from amperage? Alternator voltage test

Make sure all your accessories and lights are turned off. Have an helper rev the engine up 2500 rpm. With a multimeter set on the DC scale measure the voltage across the battery terminals. Make sure the red lead of the multimeter is on the positive battery terminal and the black lead is on the negative battery terminal. With the engine at 2500 rpm’s the voltage reading on the meter should read from 13.5 volts to 14.4 volts. It’s necessary for an alternator to generate a larger voltage than the battery's rated voltage to overcome the internal resistance of the battery. If the voltage reading on the voltmeter is 12 volts or less you could have a failed alternator.

Alternator amperage test Connect the positive lead of the multimeter to the positive output on the rear of the alternator. Now connect the negative lead of the multimeter to the negative output of the alternator. With the engine running turn on all your electric accessories and lights and raise the idle to 1200 rpm. Read the meter. The alternators amperage output must never reach its maximum available output. (Example a 90 amp alternator should run no higher than 88 amps.) If an alternator is producing it's maximum capacity amperage, it will overheat and fail. Do the following tests and post back the results. Know that amperage test is almost always overlooked when test an alternator. Even if voltage is within threshold what good is voltage with the (PUSH) from amperage? Alternator voltage test

Make sure all your accessories and lights are turned off. Have an helper rev the engine up 2500 rpm. With a multimeter set on the DC scale measure the voltage across the battery terminals. Make sure the red lead of the multimeter is on the positive battery terminal and the black lead is on the negative battery terminal. With the engine at 2500 rpm’s the voltage reading on the meter should read from 13.5 volts to 14.4 volts. It’s necessary for an alternator to generate a larger voltage than the battery's rated voltage to overcome the internal resistance of the battery. If the voltage reading on the voltmeter is 12 volts or less you could have a failed alternator.

Alternator amperage test Connect the positive lead of the multimeter to the positive output on the rear of the alternator. Now connect the negative lead of the multimeter to the negative output of the alternator. With the engine running turn on all your electric accessories and lights and raise the idle to 1200 rpm. Read the meter. The alternators amperage output must never reach its maximum available output. (Example a 90 amp alternator should run no higher than 88 amps.) If an alternator is producing it's maximum capacity amperage, it will overheat and fail.

You don't need to go nuts. If it can't put out at least 13v with everything running, lights, RWD, blower and all connections and battery known good not just known new(er) belt it snug enough, then the alternator brushes, diodes or regulator isn't up to par. Diodes can allow just enough charge to keep you going but won't overcome full use of several items.

What will screw the whole thing up is some funky aftermarket something drawing too much or wires messed up. You can buy those components separately but usually best to just swap it out for new or a quality rebuilt with warranty,

Thanks guys, just to let everyone know I replaced the alternator and now i'm getting 13.6 volts at idle. The light no longer comes on! I replaced the belt too just since it was starting to get some heat cracks in it. Thanks for the help.

It still gets me that sears would say nothing's wrong with it if the light was flashing off and on everynow and then. Unless it just happened to test normal for the few minutes they looked at it!